1. Field of the Invention
The present invention relates to an electrical connector and particularly to a Serial ATA (Advanced Technology Attachment) connector used in hard disk drives for signal transmission.
2. Description of Related Art
Serial ATA connectors provide a storage interface for ATAPI (Advanced Technology Attachment Packet Interface) devices and hard disk drives, which are main storage peripheral devices of computer systems. A conventional Serial ATA connector comprises an insulative housing defining a plurality of passageways arranged in a single row and a plurality of contacts snugly received in the passageways. The contacts include a plurality of signal and ground contacts. The ground contacts are longer than the signal contacts such that the ground contacts will engage with corresponding contacts of a complementary connector before the signal contacts for hot plugging. Each contact is equal in width along longitudinal axis thereof. However, when it is required that the impedance of the contact generally be 100xc2x10.15xcexa9, this design has difficulty to fulfill the impedance requirement of the contact. As a result, the electric capability of the electrical connector may be adversely affected. Hence, an improved electrical connector is required to overcome the disadvantages of the related art.
Accordingly, the object of the present invention is to provide an electrical connector having contacts fulfilling the impedance requirement, thereby ensuring a better electric capability of the electrical connector.
In order to achieve the object set forth, an electrical connector of the present invention comprises an insulative housing defining a plurality of passageways therein, and a plurality of contacts received in the passageways of the housing. Each contact has different widths along longitudinal axis thereof. The housing includes a plurality of inwardly extending channels communicating with corresponding passageways, a plurality of slots between adjacent passageways and a plurality of cavities each communicating with a corresponding passageway to respectively define a first clearance, a second clearance and a third clearance between each contact and the housing. As a result, each contact is surrounded by different medium, namely the air and the plastic. Further, the impedance of the contact is in direct proportion to the dielectric coefficient of the medium surrounding the contact. Since the dielectric coefficients of the air and the plastic are different, the impedance of the contact is effectively adjusted to meet the impedance requirement. On the other hand, the impedance of the contact is inversely proportional to its width. Therefore, the unequal widths of the contact are helpful for adjusting its own impedance to match the impedance requirement. Thus, the impedance requirement of the contact and the better electric capability of the electrical connector are ensured.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.